Background-aim: The use of Alzheimer’s disease (AD) biomarkers in clinical practice is becoming an important component of the diagnostic process of patients with cognitive disorders. In particular the combination of amyloid deposition and neuronal injury biomarkers it proved to be a strong indicator of an underlying AD. New amyloid radiopharmaceuticals have high lipophilicity, poten- tially making them good perfusion tracers. Therefore, the acquisition of both early (flow) and late (amyloid) post-injection imaging may lead to evaluate both brain neurodegeneration and amyloidosis at the same time. Because there is wide evidence in the literature showing that perfusion and metabolism are strongly coupled in the brain with similar patterns of hypoactivity, the aim of our study was to evaluate the concordance between flow images obtained with an early acqui- sition after 18F-Florbetapir (FBP) injection vs a traditional glucometabolic study with 18F-FDG (FDG) in a group of patients with suspected or known neurodegenerative brain involvement. Methods: We evaluated 14 patients (9M—64 ± 6.9 year) already submitted in the previous 2 months to a clinical indicated FDG PET- CT evaluation (183 ± 19 MBq). All subjects underwent a ‘‘dual- phase’’ protocol after administration of 328 ± 63 MBq of FBP. Early data were acquired from 1 to 6 min after injection of FBP. FDG and early FBP images were compared both qualitatively by two nuclear physicians unaware of FDG results, and quantitatively using a soft- ware that generated—for every study—10 volumes of interest (VOIs) for each side (corresponding to the most relevant anatomical brain regions), and calculating for each one the relative SUVmean value (SUVm). Moreover for each VOI the ratio SUVm-FDG/SUVm-FBP (SUVr) was calculated and for each patient the mean value (±1 s.d.) of this index—relatively to all brain regions—was finally assessed (20-VOIs SUVr). Results: The 20-VOIs SUVr mean values, calculated for every study patients, showed a wide range of variation (from 0.90 ± 0.07 to 2.19 ± 0.11) with the majority of subjects (79%) with values [1, indicating a greater SUVm value for FDG with respect to FBP studies. However the SUVr evaluated within the 8 cortical VOIs has proved substantially constant in every patient, showing not statistical differences in absolute values and standard deviations (p = ns) and thus confirming the strength of the correlation between metabolism and flow data in the individual subject. Interestingly SUVr values were significantly reduced in all patients only in subcortical structures (such as the basal ganglia, thalamic regions and the brain stem) in comparison to cortical VOIs (p \ 0.001). Finally the blinded analysis of FBP studies has confirmed in all 14 patients the diagnostic pattern that was formulated on the basis of FDG images. Conclusions: Our preliminary experience seem to confirm that early distribution of FBP can provide good correlation data with those obtained with FDG, potentially allowing a ‘‘one-stop-shop’’ use of dual-phase approach in the evaluation of selected subgroups of patients with cognitive impairment, with obvious advantages in terms of costs and dose savings, as compared with two separate scans. Larger prospective trials are needed to confirm these findings and to assess their potential impact in nowadays clinical practice.

Comparison of 18F-FDG vs "early phase" 18F-Florbetapir brain distribution in patients with suspected or known neurodegenerative disease

C. Cittanti
;
D. Gragnaniello;P. Milani;CRISTOFALO, Sara;V. Tugnoli;M. Bartolomei
2017

Abstract

Background-aim: The use of Alzheimer’s disease (AD) biomarkers in clinical practice is becoming an important component of the diagnostic process of patients with cognitive disorders. In particular the combination of amyloid deposition and neuronal injury biomarkers it proved to be a strong indicator of an underlying AD. New amyloid radiopharmaceuticals have high lipophilicity, poten- tially making them good perfusion tracers. Therefore, the acquisition of both early (flow) and late (amyloid) post-injection imaging may lead to evaluate both brain neurodegeneration and amyloidosis at the same time. Because there is wide evidence in the literature showing that perfusion and metabolism are strongly coupled in the brain with similar patterns of hypoactivity, the aim of our study was to evaluate the concordance between flow images obtained with an early acqui- sition after 18F-Florbetapir (FBP) injection vs a traditional glucometabolic study with 18F-FDG (FDG) in a group of patients with suspected or known neurodegenerative brain involvement. Methods: We evaluated 14 patients (9M—64 ± 6.9 year) already submitted in the previous 2 months to a clinical indicated FDG PET- CT evaluation (183 ± 19 MBq). All subjects underwent a ‘‘dual- phase’’ protocol after administration of 328 ± 63 MBq of FBP. Early data were acquired from 1 to 6 min after injection of FBP. FDG and early FBP images were compared both qualitatively by two nuclear physicians unaware of FDG results, and quantitatively using a soft- ware that generated—for every study—10 volumes of interest (VOIs) for each side (corresponding to the most relevant anatomical brain regions), and calculating for each one the relative SUVmean value (SUVm). Moreover for each VOI the ratio SUVm-FDG/SUVm-FBP (SUVr) was calculated and for each patient the mean value (±1 s.d.) of this index—relatively to all brain regions—was finally assessed (20-VOIs SUVr). Results: The 20-VOIs SUVr mean values, calculated for every study patients, showed a wide range of variation (from 0.90 ± 0.07 to 2.19 ± 0.11) with the majority of subjects (79%) with values [1, indicating a greater SUVm value for FDG with respect to FBP studies. However the SUVr evaluated within the 8 cortical VOIs has proved substantially constant in every patient, showing not statistical differences in absolute values and standard deviations (p = ns) and thus confirming the strength of the correlation between metabolism and flow data in the individual subject. Interestingly SUVr values were significantly reduced in all patients only in subcortical structures (such as the basal ganglia, thalamic regions and the brain stem) in comparison to cortical VOIs (p \ 0.001). Finally the blinded analysis of FBP studies has confirmed in all 14 patients the diagnostic pattern that was formulated on the basis of FDG images. Conclusions: Our preliminary experience seem to confirm that early distribution of FBP can provide good correlation data with those obtained with FDG, potentially allowing a ‘‘one-stop-shop’’ use of dual-phase approach in the evaluation of selected subgroups of patients with cognitive impairment, with obvious advantages in terms of costs and dose savings, as compared with two separate scans. Larger prospective trials are needed to confirm these findings and to assess their potential impact in nowadays clinical practice.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11392/2382576
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